Ringing in Speakers

Hello, i've been running Logic Pro 9 and Pro Tools Le on my new iMac which is connected to an Mbox2 which is then connected to a Soundcraft Mixing desk via Jack to Phono, the mixing desk is then connected to my KRK Speakers (Active)

I've noticed a high pitches ringing noise that comes through them if i go on any programme such as iTunes, Safari and especially on the music software, the ringing noise is also recorded when i record through Logic or Pro Tools.

i've been asking around and don't know how to stop it, some people have mentioned updating the drivers for the Mbox2?